Attosecond probing of nuclear vibrations in the D₂⁺ and HeH⁺ molecular ions

We study the ultrafast photodissociation of small diatomic molecules using attosecond laser pulses of moderate intensity in the XUV regime. The simultaneous application of subfemtosecond laser pulses with different photon energies - resonant in the region of the molecular motion - allows one to monitor the vibrational dynamics of fast diatomics, like the D2+ and HeH+ molecular ions (Biró and Csehi, accepted in J. Phys. Chem. A). In our real-time wave packet simulations, the nuclear dynamics is initiated either by sudden ionization (D2+) or by explicit pump pulses (HeH+) via distortion of the potential energy of the molecule. The application of time-delayed attosecond pulses leads to the breakup of the molecules. The information on the underlying bound-state dynamics is imprinted in the kinetic energy release (KER) spectra of the outgoing fragments (Phys. Chem. Chem. Phys. 24, 13234, 2022). We show that the KER-delay spectrograms generated in our ultrafast pump-probe schemes are able to reconstruct the most important features of the molecular motion within a given electronic state, such as the time period or amplitude of oscillations, interference patterns, or the revival and splitting of the nuclear wave packet.